Sizing paper under substantially neutral conditions with a preblend of rosin and cationic polyamide-epichlorohydrin resin



United States This invention relates to the rosin sizing of paper andmore particularly to the rosin sizing of paper at substantially neutralor slightly acid pHs.

In the seizing of paper by the usual rosin size-alum process whereinrosin size is first added to an aqueous suspension of paper pulp andpapermakers alum (aluminum sulfate) is then added to precipitae thesizing agent onto the fibers, it has generally been found diificult, ifnot impossible, to develop satisfactory sizing with most pulps unlessthe pH of the papermaking system is maintained in the range from about4.0 to about 5.5. Even under these conditions, some pulps are notreadily sized and are, therefore, designated as hard-to-size pulps.Moreover, not only does an acidic system cause corrosion of papermakingequipment, but also it has been demonstrated that paper made underacidic conditions develops less dry strength and has less strengthpermanence over a period of years. Thus, the discovery of a methodwhereby a relatively inexpensive sizing agent, such as rosin, could beefiectively applied, particularly to hard-to-size pulps, under neutralor slightly acidic pi-is should prove highly beneficial.

A principal object of the invention, therefore, is the provision of aprocess for the rosin sizing of paper which is efiective under neutralor slightly acidic conditions.

Another object of the invention is the development of better rosinsizing in paper made from pulps which are hard to size in theconventional rosin size-alum system.

Auxiliary objects of the invention are to improve wet and dry strengthsas Well as strength permanence of paper and reduce corrosion ofpaper-making equipment.

In accordance with the invention, the above and other objects areaccomplished by adding a relatively small amount of alum and a preblendof rosin size and a cationic polyamide-epichlorohydrin resin to anaqueous pulp suspension, maintaining the aqueous pulp suspension at a pHfrom about 6.0 to about 7.5, and sheeting and drying the pulp in theusual manner. The process of the invention has been found to beparticularly effective in the sizing of hard-to-size pulps such assouthern bleached kraft pulp.

Having described the invention generally, the following examples aregiven to illustrate specific embodiments thereof. Parts are by weightunless otherwise specified. The rosin size utilized in Examples l-4 and7-17 was a 3% aqueous emulsion derived from a 70% solids paste tall oilrosin size having an acid number of 23 (dry basis). The rosin sizeutilized in Examples 5, 6 and -23 was a completely saponified wood rosinsize in the form of a 3% aqueous emulsion derived from a 70% solidspaste size having an acid number of 24.

The cationic polyarnide-epichlorohydrin resin utilized in the exampleswas prepared as follows:

Two hundred twenty-five parts of diethylenetriamine and 108 parts ofwater were placed in a reaction vessel and agitated. To this was added327 parts of adipic acid.

'ice

After the acid had dissolved in the amine, the solution was heated to165-470 C. and held there until the reaction was completed. Then 503parts of Water was added. The resulting poly amide solution containedfrom 50.0% to 52.0% solids and had an intrinsic viscosity at 25 C. fromabout 0.115 to about 0.125.

The 100 parts of this polyamide solution was added about 395 parts ofWater. This solution was heated to 50 C. and 25.5 parts ofepichlorohydrin was added. The mixture was then heated at about C. untilit had attained a Gardner viscosity of DE. Then 181.8 parts of water wasadded to the product, it was cooled to 25 C. to 30 C., and suliicient10% E01 added to adjust the pH to about 5.0. The product contained about10% solids and had a Gardner viscosity of C-D.

EXAMPLES 1-6 Various pulps were beaten in demineralized water, witheither a Noble and Wood cycle heater or a Valley heater, to aSchopper-Reigier freeness of approximately 750 ml. Pulp slurries werediluted to 2.5 consistency with demineralized water and then wereadjusted to a pH of 6.87.2 with H or NaOH.

For control runs, sufiicient 3% rosin size emulsion was added to a2-liter portion of each 2.5% pulp slurry in the size crock to supply 2%of rosin size solids based on dry pulp. Papermakers alum (aluminumsulfate) was then added to reduce the slurry pH to 4.5. The treated pulpslurry was then diluted to a consistency of 0.27% in the proportionerusing acid-alum demineralized water. This dilution water was prepared byreducing the pH of demineralized water to 5.0 with sulfuric acid, thenadding enough alum to provide 5 ppm. soluble aluminurn. One-literportions of the proportioner pulp slurry were then diluted further withacid-alum demineralized water to a deckle box consistency of 0.025% inorder to form 40-pound basis weight (24" x 36500 sheet ream) handsheetusing a Noble and Wood sheetmaking apparatus. A closed white watersystem was employed. Formed sheets were wet-pressed to 33% solidscontent and then dried to 240 F. on a steam drum drier.

For runs involving the preblend process at neutral pH, a 2-liter portionof each 2.5% pulp slurry was first diluted to 0.27% consistency in theproportioner using demineralized water. There was then added 0.2%-0.4%by weight, based on the weight of dry pulp, of alum, followed by 2% byweight, solids based on the weight of dry pulp, of a 1:1 preblend ofrosin size and the abovedescribed cationic polyamide-epichlorohydrinresin. In forming the preblend, a predetermined amount of NaOH was firstadded to a 3% rosin size emulsion in order to maintain the eventualpreblend as a clear system. The cationic resin was then blended withthis alkaline size emulsion using a 3% solution of the resin. Afteradding the alum and preblend, the pH of the treated pulp slurry wasreadjusted to 6.8-7.2 with NaOH. One-liter portions of proportionerslurrry were then diluted with de mineralized water to a deckle boxconsistency of 0.025% and handsheets were formed, pressed and dried inthe same manner as described above.

All handsheets were conditioned for two days at 72 F. and 50% relativehumidity and were then tested in this environment. Resistance topenetration by Standard Feather ink was determined by use of theHercules photometer (D. Price, R. H. Osborn and I. W. Davis, TAPPI 36,42 (1953)). The time necessary for ink penetration to reduce lightreflectance to of the 3 d sheets initial value was used to represent thedegree of was produced in experiments where 01-02% alum was SlZll'lg.The sizing data are listed in Table 1. added.

T able 1 Example System Photometer No. Type of pulp Sizing process pI-Isizing (S.F.

ink, sec.)

1 27 of rosin size alum to pH 4.5 4. 5 145 g }Southern bleached kraft 1{alum 2? M1121 x i i 259 2 o rosin size a um to V .5 260 g i bleached ioz aium 2%+oi11:1 peb]ei{1d4 7. 0 219 2 0 rosinsize aurn op ..5- 4.5 263s iwestem bleached {0.5% alum 2% of 1:1 preblend 7. 0 280 The resultsindicate that the preblend sizing system at Table 3 neutral pH producedsubstantially better sizing for paper made from hard-to-size southernbleached kraft pulp Proportiona pH than was obtained using theconventional rosin size-alum Example fgj g fi system at a pH of 4.5. Thesizing produced at neutral pH added After After After 333 lit, with thepreblend for the western bleached sulfite and I alum pmblelld lggg 566-)easy-to-size western bleached kraft sheets was somewhat 1 better f4 5than obtalned by the conventional system at a pH None 69 fig 99 o 0.1 657.0 7.0 254.

One of the chief benefits of the preblend technlque, as Q2 5 9 257 shownby the above data, is the ability of this system to impart good sizingto a hard-to-size pulp (southern bleached kraft). Another benefitconferred involves the development of good sizing with rosin size in aneutral papermaking system, whereas paper made from most pulps willdevelop essentially no sizing if treated in the conventional manner in aneutral system.

EXAMPLES 7-13 Sized handsheets were prepared by treating beaten southernbleached kraft pulp in neutral, demineralized water with preblendscontaining various ratios of rosin size and thepolyamide-epichlorohydrin resin described above, after the addition of0.2% alum. The various blends were prepared by adding the resin to thesize emulsion very slowly and adding NaOH when necessary to maintain aclearsystem. Chemical additions were made to a neutral, 0.27% slurry inthe proportioner in the manner described in Examples 16, and handsheetswere formed in the usual way.

The etfect of the size/resin ratio on development of sizing in the paperis shown by the results in Table 2. A 1:1 preblend ratio gave the bestsizing, although ratios of 2:1 and 1:2 also produced good sizing. Stillhigher ratios of size/resin produced mediocre sizing, while preblendscontaining very little size led to little or no sizing development.

Table 2 Preblend composition Photometer Example sizing No. Percent (SF.ink,

Percent polyamide- Ratio, sec.) rosin size epichiorohysize/resin drinresin EXAMPLES l4-16 SiZed handsheets using varying amounts of alum and2% of ,a 1:1 preblend of rosin size and the above-describedpolyamide-epichlorohydrin resin were prepared from beaten southernbleached kraft pulp in a neutral papermaking system as described inExamples l-6. Results listed in Table 3 demonstrate the effect of thealum furnish on the sizing efliciency of the preblend. When no alunfwasadded, poor sizing was obtained. Good sizing EXAMPLES 17-19 Southernbleached kraft pulp was sized in the manner described in Examples 1-6using 0.2% alum and 2% of 1:1 preblends containing the above-describedpolyamideepichlorohydrin resin and various rosin sizing agents. Theexperiments involved regular rosin size, as utilized in Examples 1-4 and7-16, fortified rosin size, and high free rosin emulsion. All preblendswere adjusted to a pH of 11.2-11.8 with NaOI-I.

The sizing results are listed in Table 4. They show that the neutral pH,preblend sizing system is quite eifective with all three types of rosinsize.

Table 4 Preblend composition Photometer Example Polyamidesizing No.epichloro- .F.

Sizing agent hydrin ink, resin, sec.) percent 1.0% rosin size 1. 0 2611.0% fortified rosin size 1. 0 236 1.0% high free rosin emulsion 1.0 235EXAMPLES 20-23 These experiments involved southern bleached kraft,beaten and used in a distilled Water system, and western bleached kraft,beaten and used in tap water (mild alkalinity and hardness). Bothsystems were adjusted to a pH of 6 with acid or alkali. Treatment ofsouthern bleached kraft involved 0.5% alum, 1% rosin size (completelysaponified) and 0.5 of the above-described 'polyamide-epichlorohydrinresin. The size and resin were added (1) as a preblend to the crockbefore the alum and (2) as a preblend after alum at the proportioner.

Treatment of :western bleached kraft involved 0.5% 'alum,'1% rosin size,and 0.5% of the above-described 'polyamide-epichlorohydrin resin addedin the same two .ways described above. Aside from method and point ofaddition, the sizing and sheetmaking procedures were es sentially thesame as described in Examples 1-6.

The results listed in Table 5 show that preblend addition at theproportioner is the most eitective sizing procedure where southernbleached kraft is concerned, whereas addition to the size crock is themost eff ctive sizing procedure where western bleached krait isconcerned.

mole, per mole of rosin, of an acidic compound containing the groupincluding a,B-unsaturated monobasic and polybasic organic acids and acidanhydrides such as acrylic, maleic, fumaric, itaconic and c-itraconicacids and their anhy- Tuba: 5

Chemical additions Handshect properties Ex. Pho- No. Basis tometer Tosize crock To proportioner weight sizing (lb/R.) (S.F. ink, 1 sec.) I

(Southern bleached Matt-distilled water system at pH=6) 20....Size-resin preb1end 0.5% alum 4... 1 202 21.. 0.5% alum pr 40. 7 356(Western bleached kraittap Water system at pH=6) 22.... Size-resinpreblend 0.5% alum 40. 3 618 23. 0.5% alum sizeresin preblend 39. 2 315In accordance with the invention, a small amount of alum and a preblendof rosin size and cationic polyamideepichlorohydrin resin in a Weightratio of rosin size to resin of from about 2:1 to about 122 are added toa dilute slurry of paper pulp in a substantially neutral papermakingsystem. In the case of a hard-to-size pulp, and where the alum is addedbefore the resin size-resin preblend, this treatment develops bettersizing than can be obtained for this type of pulp by the conventionalrosin size-alum system at any pH. In the case of an easy-tosize pulp,such as Western bleached kraft, better sizing is Y obtained by addingthe preblend and then the alum to the size crock than is obtained byadding these in the reverse order to the proportioner. While the alumand the preblend can thus be added in any desired order, includingsimultaneously, optimum results in the case of hard-tosize pulps, towhich the process of the invention is particularly applicable, areobtained if the alum is added first. This, therefore, is the preferredprocedure.

The pH of the papermaking system should be maintained within the rangefrom about 6.0 to about 7.5 in order to realize the advantages of theinvention. However, the preterred pH range is from about 6.8 to about7.2. The amount of preblend added can be varied from about 0.5% to about5% or more by weight, based on the Weight of dry pulp. The amount ofalum added to the system can range from about 0.1% to 0.5% or even more,say up to about 2%, as long as the system is adjusted to, and maintainedat, a pH from about 6.0 to about 7.5.

The term hard to size, as utilized herein, means pulps which aregenerally difiicu-lt to size by the conventional rosin size-alurnprocess. In general, highly purified (e.g., high tx-CfilllllOSB) pulpssuch as southern bleached kraft, certain types of bleached sulfite,cotton linters, and rag fibers are hard to size.

The term rosin size, as used herein, means any of the rosin sizes knownto the art and includes sizes made from wood rosin, gum rosin, and talloil rosin in crude or refined state and/ or after treatment of variouskinds to increase its effectiveness for the intended purpose. it alsoincludes sizes made from modified rosins, such as partially orsubstantialiy completely hydrogenated rosins and polymerized rosins, aswell as rosins which have been heat treated, reacted with formaldehyde,or otherwise treated to inhibit crystallization of the rosin or sizespreprepar'ed therefrom.

Sizes prepared from rosins containing or which have been admixed withvarious fortifying agents can also be used. Rosin compositions of thistype are desirably prepared by reacting rosin with from one-twentieth toone drides. Products of this type and methods of preparing and usingsame are well known as shown, for example, in US. 2,628,918 and US.2,684,300.

The invention also contemplates the use of sizes prepared from rosins orrosin compositions, such as that described above, containing varyingamounts of fatty acids or fatty acid mixtures. For example, there can beused a tall oil rosin fraction obtained by the fractional distillationof tall oil and containing up to several percent of a tall oil fattyacid mixture.

In the preparation of these sizes, e.g., sizes containing from about 50%to about 86% or more total solids, the rosin is warmed to about -150 C.,preferably (3., and aqueous alkali, i.e., aqueous alkali metal hydroxideor carbonate, is added. During this addition, the temperature graduallyreduces and heat is applied, as required, until the reaction issubstantially complete. Sufficient water can be added in the aqueousalkali to provide the desired total solids in the paste, or,alternatively, water may be added or removed during or after thereaction to obtain the desired solids. The amount of alkali used willdepend on the degree of saponification or neutralization desired.Generally, a partial neutralization of the rosin acids to the extent offrom about 7( to about 95% is desirable unless the paste is to beconverted to a dry size, in which event substantially completeneutralization is preferred.

The cationic polyamide-epichlorohydrin resins contemplated for useherein are Water-soluble polymeric condensation products ofepichlorohydrin and a polyamide derived from a polyalkylene polyamineand an aliphatic dicarboxylic acid. In the preparation of theseproducts, the dicarboxylic acid is first reacted with a polyalkylenepolyarnine under conditions such as to produce a waters-oluble polyamidecontaining the recurring groups where n and are each two or more and Ris the divalent hydrocarbon radical of the dicarboxylic acid. Thiswatersoluble polyarnide is then reacted with epichlorohydrin to form aWater-soluble cationic thermosetting resin.

The dicarboxylic acids contemplated for use in preparing these resinsare diglycolic acid and saturated aliphatic dicarboxylic acidspreferably containing from 3 to 8 carbon atoms such as succinic,glutaric, adipic and the like. Of these, diglycolic acid and thesaturated aliphatic dicanboxylic acids having from 4 to 6 carbon atomsin the molecule, namely, succinic, glutaric and adipic, are mostpreferred. Blends of two or more of these dicarboxylic acids may also beused, as well as blends of one or more of these with higher saturatedaliphatic dicarboxylic acids such as azelaic and sebacic as long as theresulting longchain polyamide is water soluble.

A variety of polyalkylene polyamines including polyethylene polyamines,polypropylene polyamines, polybutylene polyamines and so on may beemployed herein of which the polyethylene polyamines represent aneconomically preferred class. More specifically, the polyalkylenepolyamines contemplated for use herein are polyamines containing twoprimary amine groups and at least one secondary amine group in which thenitrogen atoms are linked together by groups of the formula -C,,H wheren is a small integer greater than unity and the number of such groups inthe molecule ranges from two up to about eight, and preferably up toabout four. The nitrogen atoms may be attached to adjacent carbon atomsin the group C,,H or to carbon atoms further apart, but not to the samecarbon atom. This invention contemplates not only the use of suchpolyamines as diethylenetriamine, triethylenetetramine,tetraethylenepentamine, dipropylenetriamine, and the like, which can beobtained in reasonably pure form, but also mixtures and various crudepolyamine materials. For example, the mixture of polyethylene polyaminesobtained by the reaction of ammonia and ethylene dichloride, refinedonly to the extent of removal of chlorides, water, excess ammonia, andethylenediamine, is a very satisfactory starting material. Mostpreferred are the polyethylene polyamines containing from two to fourethylene groups, two primary amine groups,

and from one to three secondary amine groups.

The term polyalkylene polyamine employed in the claims, therefore,refers to and includes any of the polyalkylene polyamines referred toabove or to a mixture of such polyalkylene polyamines.

It is desirable, in some cases, to increase the spacing of secondaryamine groups on the polyamide molecule in order to change the reactivityof the polyamide-epichlorohydrin complex. This can be accomplished bysubstituting an aliphatic diamine such as ethylenediamine,propylenediamine, hexamethylenediamine or a heterocyclic diamine such aspiperazine or the like for a portion of the polyalkylene polyamine. Forthis purpose, up to about 60% of the polyalkylene polyamine may bereplaced by a molecularly equivalent amount of the diamine. Usually, areplacement of about 30% or less will serve the purpose.

The temperatures employed for carrying out the reaction between thedicarboxylic acid and the polyalkylene polyamine may vary from about 110C. to about 250 C. or higher at atmospheric pressure. For most purposes,however, temperatures between about 160 C. and 210 C. have been foundsatisfactory and are preferred. Where reduced pressures are employed,somewhat lower temperatures may be utilized. The time of reactiondepends on the temperatures and pressures utilized and will ordinarilyvary from about /2 to 2 hours, although shorter or longer reaction timesmay be utilized depending on reaction conditions. In any event, thereaction is desirably continued to substantial completion for bestresults.

In carrying out the reaction, it is preferred to use an amount ofdicarboxylic acid sufiicient to react substantially completely with theprimary amine groups of the polyalkylene polyamine but insufficient toreact with the secondary amine groups to any substantial extent. Thiswill usually require a mole ratio of polyalkylene polyamine todicarboxylic acid of from about 0.9:1 to about 1.221, and preferablyfrom about 0.92:1 to 1.14:1. However, mole ratios of from about 0.811 toabout 1.421 may be used with quite satisfactory results. Mole ratiosoutside of these ranges are generally unsatisfactory. Thus,

" mole ratios below about 0811 result in a gelled product or one havinga pronounced tendency to gel, While mole ratios above 1.4:1 result inlow molecular weight polyamides.- Such products do not produce efficientresins for'the purpose herein described when reacted withepichlorohydrin.

In converting the polyamide, formed as above described, to a cationicthermosetting resin, it is reacted with epichlorohydrin at a temperaturefrom about 45 C. to about C., and preferably between about 45 C. and 70C., until the viscosity of a 20% solids solution at 25 C. has reachedabout C or higher on the Gardner-Holdt scale. This reaction ispreferably carried out in aqueous solution to moderate the reaction. pHadjustment is usually not necessary. However, since the pH decreasesduring the polymerization phase of the reaction, it may be desirable, insome cases, to add alkali to combine with at least some of the acidformed.

When the desired viscosity is reached, sufficient water is then added toadjust the solids content of the resin solution to the desired amount,the product cooled to about 25 C. and then stabilized by addingsufiicient acid to adjust the pH to about 6, and preferably to about 4or less, e.g., from about 2 to about 4. Any suitable acid such ashydrochloric, sulfuric, nitric, formic, phosphoric, and acetic acid maybe used to stabilize the product.

In the polyamide-epichlorohydrin reaction, it is preferred to usesuificient epichlorohydrin to convert all secondary amine groups totertiary amine groups and/or quarternary ammonium groups includingcyclic structures. However, more or less may be added to moderate orincrease reaction rates. In general, it is contemplated utilizing fromabout 0.5 mole to about 1.8 moles of epichlorohydrin per mole polyamidesecondary amine. It is preferred to utilize from about 0.9 mole to about1.5 moles of epichlorohydrin per mole of polyamide secondary aminegroup. 7

The present invention provides a number of important advantagesincluding (1) the provision of a method for effectively sizing ahard-to-size pulp, e.g., southern bleached kraft pulp which has beenbleached withchlorine dioxide, and (2) the provision of a method foreffectively sizing various pulps in a neutral papermaking system,thereby avoiding or reducing the corrosion difiiculties which areencountered in an acidic papermaking system. In additon to the above,the process of the invention results ina Well-sized sheet of improveddry strength, wet strength, and strength permanence. Thus, reducing theenvironmental acidity contributes to both dry strength and itspermanence, while the introduction of cationic polyamide-epichlorohydrinresin improves both wet and dry strength.

The present invention is particularly useful in mills where ahard-to-size pulp must be converted into a wellsized paper and in millswhere a high pH paperrnaking system is required or where it is desiredin order to reduce equipment corrosion. It is also useful in any millwhere the fringe benefits of improved sheet wet strength, dry strength,and strength permanence are desired, together with sizing.

What I claim and desire to protect by Letters Patent is:

l. The method of sizing paper which comprises adding to an aqueous pulpsuspension at a pH from about 6.0 to about 7.5 from about 0.1% to about2% by weight, based on the dry weight of pulp, of alum and from about0.5% to about 5.0% by weight, based on the dry weight of pulp, of apreblend of rosin size and a cationic polyamideepichlorohydrin resin ina weight ratio of rosin size to resin of from about 5:1 to about 1:2,said cationic polyamide-epichlorohydrin resin being obtained by reactinga polyalkylene polyamine with a dicarboxylic acid selected from thegroup consisting of diglycolic acid and C -C saturated aliphaticdicarboxylic acids. in a mole ratio of from about 0.8 to about 1.4 ofthe former to about 1.0 of the latter to form a long-chain polyamide,and then reacting the polyamide with epichlorohydrin in a mole ratio ofepichlorohydrin to secondary amine groups of said polyamide of fromabout 0.511 to about 1 .821, maintaining the pH of the aqueous pulpsuspension from about 6.0 to about 7.5, and forming the pulp intosheets.

2. The method of sizing paper which comprises adding to an aqueous pulpsuspension at a pH from about 6.0 to about 7.5 from about 0.1% to about0.5% by Weight, based on the dry weight of pulp, of alum, adding to theresulting suspension from about 0.5% to about by weight, based on thedry Weight of pulp, of a preblend of rosin size and a cationicpolyamide-epichlorohydrin resin obtained by reacting a polyalkylenepolyaminc with a dicarboxylic acid selected from the group consisting ofdiglycolic acid and C -C saturated aliphatic dicarboxylic acids in amole ratio of from about 0.8 to about 1.4 of the former to about 1.0 ofthe latter to form a long-chain polyainide, and then reacting thepolyamide with epichlorohydrin in a mole ratio of epichlorohydrin tosecondary amine groups of said polyamide of from about 0.5:1 to about1.8:1, the ratio of rosin size to resin in said preblend being fromabout 2:1 to about 1:2, maintaining the pH of the aqueous pulpsuspension from about 6.0 to about 7.5, and forming the pulp intosheets.

3. The method in accordance with claim 1 wherein the rosin size is afortified rosin size containing the reaction product of rosin with fromone-twentieth to one mole, per mole of rosin, of an acidic compoundcontaining the group.

4. The method in accordance with claim 1 in which the rosin size isprepared from a tall oil rosin fraction derived from tall oil.

10 5. The method in accordance with claim 2 wherein the rosin size is afortified rosin size containing the reaction product of rosin with fromone-twentieth to one mole, per mole of rosin, on an acidic compoundcontaining the \C=C 0:0 l I group.

6. The method in accordance with claim 2 in which the rosin size isprepared from a tall oil rosin fraction derived from tall oil.

References fitted by the Examiner UNITED STATES PATENTS 1,840,399 1/32Lane 162179 2,544,887 3/51 Leonard 162180 2,601,597 6/52 Daniel et al162164 2,926,116 2/60 Keim 162-464 2,994,635 8/ 61 Reaville et a1.162-179 3,096,231 7/63 Griggs et a1 162-179 FOREIGN PATENTS 10,760 1845Great Britain. 461,272 2/37 Great Britain. 711,404 6/ 54 Great Britain.790,198 9/ France.

DONALL H. SYLVESTER, Primary Examiner. MORRIS O. WOLK, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,186,900 June 1, 1965 Frederick B. De Young It is hereby certified thaterror a ppears in the above numbered patent requiring correction andthat the sa id Letters Patent should read as corrected below.

Column 1, line 14, for "acid" read acidic line 15, for "seizing" readsizing column 2, line 7, for "The" read To Signed and sealed this 19thday of October 1965.

'SEAL) Quest:

RNEST W. SWIDER EDWARD J. BRENNER testing Officer Commissioner ofPatents

1. THE METHOD OF SIZING PAPER WHICH COMPRISES ADDING TO AN AQUEOUS PULPSUSPENSION AT A PH FROM ABOUT 6.0 TO ABOUT 7.5 FROM ABOUT 0.1% TO ABOUT2% BY WEIGHT, BASED ON THE DRY WEIGHT OF PULP, OF ALUM AND FROM ABOUT0.5% TO ABOUT 5.0% BY WEIGHT, BASED ON THE DRY WEIGHT OF PULP, OF APREBLEND OF ROSIN SIZE AND A CATIONIC POLYAMIDEEPICHLOROHYDRIN RESIN INA WEIGHT RATIO OF ROSIN SIZE TO RESIN OF FROM ABOUT 5:1 TO ABOUT 1:2,SAID CATIONIC POLYAMIDE-EPICHLOROHYDRIN RESIN BEING OBTAINED BY REACTINGA POLYALKYLENE POLYAMINE WITH A DICARBOXYLIC ACID SELECTED FROM THEGROUP CONSISTING OF DIGLYCOLIC ACID AND C3-C8 SATURATED ALIPHATEICDICARBOXYLIC ACIDS IN A MOLE RATIO OF FROM ABOUT 0.8 TO ABOUT 1.4 OF THEFORMER TO ABOUT 1.0 OF THE LATTER TO FORM A LONG-CHAIN POLYAMIDE, ANDTHEN REACTING THE POLYAMIDE WITH EPICHLOROHYDRIN IN A MOLE RATIO OFEPICHLOROHYDRIN TO SECONDARY AMINE GROUPS OF SAID POLYAMIDE OF FROMABOUT 0.5:1 TO ABOUT 1.8:1, MAINTAINING THE PH OF THE AQUEOUS PULPSUSPENSION FROM ABOUT 6.0 TO ABOUT 7.5, AND FORMING THE PULP INTOSHEETS.